CORALS AND BRYOZOA. 193 



NEMATAXIS, Hall. 1886. 



(See page 74. ) 



Nemataxis simplex. 



PLATE LXVI. FIGS. 17-19. 



ZoARiUM ramose, solid; bifurcations very infrequent; branches 1.50 mm. in 

 diameter. Cells tubular, arising from the center of the branch, oblique, 

 making a sinuous curve, in contact for the greater portion of their length, 

 separating at a very short distance from the surface. Cell apertures oval, 

 length about .16 mm., width two-thirds the length, disposed in parallel, 

 longitudinal rows ; sometimes alternating and forming obliquely transverse 

 rows ; separated by about one-half the length of the aperture, about eight- 

 een rows on a branch. Peristomes very slight or entirely wanting. Surface 

 between the apertures elevated, convex, finely granulose. In some con- 

 ditions of weathering the peristomes are elevated and the surface between 

 the cell apertures is flat. 



This species is easily distinguished from N. fibrosus of the Upper Helderberg 

 group, the only other species of this genus at present known, by its much 

 smaller size. The surface has some resemblance to that of Badropora grani- 

 striata, but the cell apertures are much smaller, and the space between them 

 much narrower. 



Formation and locality. Hamilton group, Darien Centre, Erie county, N. Y. 



BACTROPORA, nov. gen. 

 Bactbopora granistbiata. 



•PLATE LXVI, FIGS. 20-28. 



Tretnatopiyraf granistrlata, Hall. Trans. Albany Institute, vol. x, p. 182. 1881. 

 " " " Report of State Geologist for 1883, p. 13. 1884. 



ZoARiOM ramose, solid ; bifurcations distant ; base tapering, acute at the apex, 

 finely striated, striae minutely granulose. Cells tubular, arising from the center 

 of the branch, oblique, curved, walls comparatively thick ; septa thin and 



